How do you find range using hydrophone and sonar?

Realplayer · 12-29-07, 08:25 AM

Hi Subsim freaks,

i play GWX and have November 1943 and it starts to get hard (manual targeting etc.)

My litte problem is to find out the range to a sonar contact when the sub is submerged and i have no visual contact. I try to ask the sonarman - normal and "accurate" - and i try the sonar button, my u-boat is of course equipped with sonar.

But: all three methods result in similar, but wrong solutions. if i hit the sonar button repeatedly, the range gets longer and longer, even when i am sure that the contact is moving towards me. Most of the time range is shown between 4 km and 6 km, even if it is much closer.

How do you handle this? I must keep a long distance to the contacts before i dive, otherwise the dd's detect me with their radar and hunt me.

Packerton · 12-29-07, 11:29 AM

Theirs a very detailed Video Tutorial of this on the web somewhere, let me see if I can find it for you.

And welcome to Subsim Herr Kaluen Realplayer!!!!

The Butcher · 12-29-07, 01:19 PM

The line on the Nav map is just a little longer than the actual contact. If you use the track closest contact command for your Sonarman he will give you constant updates. Make a mark and time 3 min 15 sec measure between them and you have its speed. You can line up and fire torpedoes without ever raising your periscope if need be. This link is a step by step I use in dense fog. I learned it from the sound trainer by Greyrider and Captain Nautilus. If you don't put up your periscope you wont be temped to sit and watch your shot while all those hunters lock on to you.

http://www.subsim.com/radioroom/show...593#post715593

Canovaro · 12-29-07, 02:41 PM

Search this forum for "sound trainer". I'm sure you'll find it.
There is a lot of indepth info about hydrohunting.

abclkhan · 12-30-07, 05:15 PM

Hello

You dot need active sonar to plot a good interception course. Use only passive hydrophones.
Do the following:
1) You are submerged and get a contact. Stop the boat and take note of:
a. your course
b. your exact position
c. The bearing.
Note: To determine the exact bearing, move the pointer slowly until u start rearing a faint sound of a ship. Every contact takes 20o. Take the bearing and sum / diminish 10. Doind this, you will find the center of the 20o cone. So, if you start rearing sound at 93, the ship will be at 83degrees. copy?

2) Take new bearings each 10 to 30 minutes, repeat 2 times, so u ll have at the end 3 bearings.

3) Plot them on the navmap.

4) Now start moving at full speed, trying to move to the same side of the ship. I mean... if it goes to starboard, set any course to starboard. If its going east go east. if it goes west go west. You may surface but it can be risky in late war.

5) Leave your ship moving and go to nav map, and draw a circle with the compass.
The circle must have its arrow directed horizontally to any side you want.

6) now, take the proctator. Click in the center and see the horizontal arrow. Now, if the ship is coming from your left, take the protactor's central point to left side of the circle's diameter.

7) Now, before clicking again, take your appointments. Take the difference between the first and the second bearings. I will call it angle "D". Calculate this: (180 - 2D) / 2. With the result of this equationin mind, direct the second extremity of the proctator to below the circle, at an angle = to the ... result of the equation.

8) Take the proctator again and draw another angle from the left side of the diameter of the circle, passing through the center, and direct it to below the circle with the same angle of the equation. Now, you should have a triangle.

9) Repeat these steps to draw another triangle this time within the right side of the diameter, but use the difference of the 2nd and 3th bearings. Now you have two triangles (isosceles triangles).

10) Use compass to draw a circle from the vertices of each triangle to the center of your circle. The new circles should cross themselves in two points: one at the center of the old circle, other in a position we will call "S".

11) Draw an angle from "S" , anchor it on the left side of the old circle's diameter and direct it along the diameter, to right. Get the resulting angle....

12) ...And use it to draw an angle from your first position, to any point in the first
line of bearing, directed to east, just like your target.

13) Now you have its course.

14) After 30 min at full speed, stop th boat and take a new bearing, your new position, and actul course. Draw this new bearing.

15) Observe how the line we called the course of the target, as it crosses the other bearing lines.... intervals are supposed to be equal to each other. Sum This interval along the course line from the 3th bearing line, and you' ll have the 4th bearing, which you would detet if you were still at the first position.

16) Observe the 4th bearing line as it crosses the actual bearing you have plotted from your new position, and you will have its current position. with this in hands, you can calculate the speed.

As it is an approximation, when u have the ship in front of the scope, take a definitive reading of the speed...

It is kinda hard to understand as you see for the first time, but works fine, just be certain to get a consistent bearing variation.
Active sonar gives your position to escorts... i dont like to use. I hope my english is clear enough for you to understand

raduz · 12-31-07, 05:29 AM

http://www.subsim.com/radioroom/show....php?t=107303&

difool2 · 12-31-07, 03:28 PM

My method is even easier, and if the contact is in fact on a bearing bringing you closer to your boat (sonar man says "closing!") it is virtually foolproof, even if you don't get an exact AOB (until a peek thru the scope when it is close confirms the AOB).

Each time you get a reading draw a line from your boat to the contact's heading.

When the contact is first acquired, drive straight towards it to guage whether it moving to the starboard or port. Once you confirm that then angle your boat about 60 or so degrees off that heading to set up an intercept course. [the heading you choose depends on the speeds of both your boat and his ship and a few other things which are more intuitive than hard-and-fast]

Get periodic readings of his headings at regular intervals. What you want to do is keep the bearing of the contact in a constant direction (such as 60 as stated above). If he starts to close the bearing down to 0 then he is outrunning you to the interception point, in which case you may need to speed up and/or alter your course to an optimal heading (which in a non-XXI probably would involve surfacing and running at high speed).

If the bearing starts to get larger then you are outrunning him and will beat him to the interception point. If the bearing remains steady you will both arrive at that point simultaneously-naturally since you want to take a shot then you need to allow about 1,000 meters or so of room for you to shoot.

If you do it right and keep on steaming fearlessly ahead, you'll actually collide, which almost happened to me last night with a Norwegian freighter (which was neutral at the time and thus I couldn't have shot it anyway)-had to hurriedly order a crash dive and retract my scope and I just barely avoided his hull!

joegrundman · 12-31-07, 07:49 PM

I use a very similar method to difool2, but i believe that it can be proven that an intercept angle of 80 degrees is optimal for intercepting the greatest possible range of targets.

If you find you are gaining ground easily, then you can reduce the intercept angle to speed things up.

In fact using this method, if you can make estimates regarding target speed, then you can also calculate target course, especially if you have a KM whiz wheel.

In addition there is even a way to get range too

There's a tutorial i wrote on the subject which you can download from the filefront in my sig.

joe

Pisces · 02-11-08, 06:19 PM

Mittelwaechter made a movie quite a while ago on how to do a passive hydrophone hunt. I asked him privately if he could re-upload it, which he did recently. He was lucky to find it on one of his old harddrives. The way he does it looks very much like abclkhan's steps.

The movie is a very good quality. It is not your regular movie format though, it's a self-playing AVI (so actually a .exe) compressed by using RAD Game tools. The fact that is an .exe may scare you wrt virusses and so on. But I find there is no reason for that. My virusscanner (AVG 7.5) is perfectly happy with it. And my pc isn't acting up yet either. But that is ofcourse no guaranty.

A drawback is that it plays no sound and that it is in 512/384 pixels, and not fullscreen. But if you add " /W1024 /H768" at the end of the filename in a shortcut to the file it will stretch the movie to those dimensions (or whatever you desire).

Get it while it is still there:

http://rapidshare.de/files/38491800/...oHunt.exe.html

T.Von Hogan · 02-12-08, 02:15 AM

I don't , i use the periscope.

joegrundman · 02-12-08, 02:30 AM

Sometimes visibilty is very poor

Pisces · 02-12-08, 10:10 AM

And hydrophone can hear atleast twice as far as 16km visual periscope range.

12-29-07, 08:25 AM	#1
Realplayer Watch Join Date: Jul 2005 Location: Austria Posts: 18 Downloads: 52 Uploads: 0	How do you find range using hydrophone and sonar? Hi Subsim freaks, i play GWX and have November 1943 and it starts to get hard (manual targeting etc.) My litte problem is to find out the range to a sonar contact when the sub is submerged and i have no visual contact. I try to ask the sonarman - normal and "accurate" - and i try the sonar button, my u-boat is of course equipped with sonar. But: all three methods result in similar, but wrong solutions. if i hit the sonar button repeatedly, the range gets longer and longer, even when i am sure that the contact is moving towards me. Most of the time range is shown between 4 km and 6 km, even if it is much closer. How do you handle this? I must keep a long distance to the contacts before i dive, otherwise the dd's detect me with their radar and hunt me.

12-29-07, 11:29 AM	#2
Packerton Sonar Guy Join Date: Apr 2007 Location: Newfoundland,Canada Posts: 398 Downloads: 6 Uploads: 0	Theirs a very detailed Video Tutorial of this on the web somewhere, let me see if I can find it for you. And welcome to Subsim Herr Kaluen Realplayer!!!! __________________ GWX crew member. Come Hell or High water, we get it done!

12-29-07, 01:19 PM	#3
The Butcher Loader Join Date: Nov 2007 Location: U.S.A. Posts: 85 Downloads: 40 Uploads: 0	Hydrophone The line on the Nav map is just a little longer than the actual contact. If you use the track closest contact command for your Sonarman he will give you constant updates. Make a mark and time 3 min 15 sec measure between them and you have its speed. You can line up and fire torpedoes without ever raising your periscope if need be. This link is a step by step I use in dense fog. I learned it from the sound trainer by Greyrider and Captain Nautilus. If you don't put up your periscope you wont be temped to sit and watch your shot while all those hunters lock on to you. http://www.subsim.com/radioroom/show...593#post715593

12-31-07, 07:49 PM	#8
joegrundman Ocean Warrior Join Date: May 2007 Posts: 2,689 Downloads: 34 Uploads: 0	I use a very similar method to difool2, but i believe that it can be proven that an intercept angle of 80 degrees is optimal for intercepting the greatest possible range of targets. If you find you are gaining ground easily, then you can reduce the intercept angle to speed things up. In fact using this method, if you can make estimates regarding target speed, then you can also calculate target course, especially if you have a KM whiz wheel. In addition there is even a way to get range too There's a tutorial i wrote on the subject which you can download from the filefront in my sig. joe __________________ "Enemy submarines are to be called U-Boats. The term submarine is to be reserved for Allied under water vessels. U-Boats are those dastardly villains who sink our ships, while submarines are those gallant and noble craft which sink theirs." Winston Churchill

02-12-08, 02:30 AM	#11
joegrundman Ocean Warrior Join Date: May 2007 Posts: 2,689 Downloads: 34 Uploads: 0	Sometimes visibilty is very poor __________________ "Enemy submarines are to be called U-Boats. The term submarine is to be reserved for Allied under water vessels. U-Boats are those dastardly villains who sink our ships, while submarines are those gallant and noble craft which sink theirs." Winston Churchill

12-29-07, 02:41 PM	#4
Canovaro Ace of the Deep Join Date: Mar 2007 Location: Netherlands Posts: 1,062 Downloads: 34 Uploads: 0	Search this forum for "sound trainer". I'm sure you'll find it. There is a lot of indepth info about hydrohunting.

12-30-07, 05:15 PM	#5
abclkhan Loader Join Date: Nov 2006 Posts: 87 Downloads: 169 Uploads: 0	Hello You dot need active sonar to plot a good interception course. Use only passive hydrophones. Do the following: 1) You are submerged and get a contact. Stop the boat and take note of: a. your course b. your exact position c. The bearing. Note: To determine the exact bearing, move the pointer slowly until u start rearing a faint sound of a ship. Every contact takes 20o. Take the bearing and sum / diminish 10. Doind this, you will find the center of the 20o cone. So, if you start rearing sound at 93, the ship will be at 83degrees. copy? 2) Take new bearings each 10 to 30 minutes, repeat 2 times, so u ll have at the end 3 bearings. 3) Plot them on the navmap. 4) Now start moving at full speed, trying to move to the same side of the ship. I mean... if it goes to starboard, set any course to starboard. If its going east go east. if it goes west go west. You may surface but it can be risky in late war. 5) Leave your ship moving and go to nav map, and draw a circle with the compass. The circle must have its arrow directed horizontally to any side you want. 6) now, take the proctator. Click in the center and see the horizontal arrow. Now, if the ship is coming from your left, take the protactor's central point to left side of the circle's diameter. 7) Now, before clicking again, take your appointments. Take the difference between the first and the second bearings. I will call it angle "D". Calculate this: (180 - 2D) / 2. With the result of this equationin mind, direct the second extremity of the proctator to below the circle, at an angle = to the ... result of the equation. 8) Take the proctator again and draw another angle from the left side of the diameter of the circle, passing through the center, and direct it to below the circle with the same angle of the equation. Now, you should have a triangle. 9) Repeat these steps to draw another triangle this time within the right side of the diameter, but use the difference of the 2nd and 3th bearings. Now you have two triangles (isosceles triangles). 10) Use compass to draw a circle from the vertices of each triangle to the center of your circle. The new circles should cross themselves in two points: one at the center of the old circle, other in a position we will call "S". 11) Draw an angle from "S" , anchor it on the left side of the old circle's diameter and direct it along the diameter, to right. Get the resulting angle.... 12) ...And use it to draw an angle from your first position, to any point in the first line of bearing, directed to east, just like your target. 13) Now you have its course. 14) After 30 min at full speed, stop th boat and take a new bearing, your new position, and actul course. Draw this new bearing. 15) Observe how the line we called the course of the target, as it crosses the other bearing lines.... intervals are supposed to be equal to each other. Sum This interval along the course line from the 3th bearing line, and you' ll have the 4th bearing, which you would detet if you were still at the first position. 16) Observe the 4th bearing line as it crosses the actual bearing you have plotted from your new position, and you will have its current position. with this in hands, you can calculate the speed. As it is an approximation, when u have the ship in front of the scope, take a definitive reading of the speed... It is kinda hard to understand as you see for the first time, but works fine, just be certain to get a consistent bearing variation. Active sonar gives your position to escorts... i dont like to use. I hope my english is clear enough for you to understand

12-31-07, 05:29 AM	#6
raduz Engineer Join Date: Sep 2006 Location: Slovakia Posts: 205 Downloads: 3 Uploads: 0	http://www.subsim.com/radioroom/show....php?t=107303&

12-31-07, 03:28 PM	#7
difool2 Commander Join Date: Apr 2005 Posts: 459 Downloads: 31 Uploads: 0	My method is even easier, and if the contact is in fact on a bearing bringing you closer to your boat (sonar man says "closing!") it is virtually foolproof, even if you don't get an exact AOB (until a peek thru the scope when it is close confirms the AOB). Each time you get a reading draw a line from your boat to the contact's heading. When the contact is first acquired, drive straight towards it to guage whether it moving to the starboard or port. Once you confirm that then angle your boat about 60 or so degrees off that heading to set up an intercept course. [the heading you choose depends on the speeds of both your boat and his ship and a few other things which are more intuitive than hard-and-fast] Get periodic readings of his headings at regular intervals. What you want to do is keep the bearing of the contact in a constant direction (such as 60 as stated above). If he starts to close the bearing down to 0 then he is outrunning you to the interception point, in which case you may need to speed up and/or alter your course to an optimal heading (which in a non-XXI probably would involve surfacing and running at high speed). If the bearing starts to get larger then you are outrunning him and will beat him to the interception point. If the bearing remains steady you will both arrive at that point simultaneously-naturally since you want to take a shot then you need to allow about 1,000 meters or so of room for you to shoot. If you do it right and keep on steaming fearlessly ahead, you'll actually collide, which almost happened to me last night with a Norwegian freighter (which was neutral at the time and thus I couldn't have shot it anyway)-had to hurriedly order a crash dive and retract my scope and I just barely avoided his hull!

02-11-08, 06:19 PM	#9
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,904 Downloads: 304 Uploads: 0	Mittelwaechter made a movie quite a while ago on how to do a passive hydrophone hunt. I asked him privately if he could re-upload it, which he did recently. He was lucky to find it on one of his old harddrives. The way he does it looks very much like abclkhan's steps. The movie is a very good quality. It is not your regular movie format though, it's a self-playing AVI (so actually a .exe) compressed by using RAD Game tools. The fact that is an .exe may scare you wrt virusses and so on. But I find there is no reason for that. My virusscanner (AVG 7.5) is perfectly happy with it. And my pc isn't acting up yet either. But that is ofcourse no guaranty. A drawback is that it plays no sound and that it is in 512/384 pixels, and not fullscreen. But if you add " /W1024 /H768" at the end of the filename in a shortcut to the file it will stretch the movie to those dimensions (or whatever you desire). Get it while it is still there: http://rapidshare.de/files/38491800/...oHunt.exe.html

02-12-08, 02:15 AM	#10
T.Von Hogan Planesman Join Date: Oct 2007 Location: mississippi Posts: 190 Downloads: 51 Uploads: 0	I don't , i use the periscope.

02-12-08, 10:10 AM	#12
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,904 Downloads: 304 Uploads: 0	And hydrophone can hear atleast twice as far as 16km visual periscope range.